Ignore them. You are not obliged or legally held to talk to any 3rd party company over your previous IVA or your current finances. If they continue to call you can report them.
Last Payment made 04/12/14. Completion Certificate 25/7/15. IVA company GT. No Issues
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk